Abstract
To date, the investigation of genes involved in Al resistance has focused mainly on microarrays and short periods of Al exposure. We investigated genes involved in the global response under Al stress by tracking the expression profile of two inbred popcorn lines with different Al sensitivity during 72 h of Al stress. A total of 1003 differentially expressed genes were identified in the Al-sensitive line, and 1751 were identified in the Al-resistant line, of which 273 were shared in both lines. Genes in the category of “response to abiotic stress” were present in both lines, but there was a higher number in the Al-resistant line. Transcription factors, genes involved in fatty acid biosynthesis, and genes involved in cell wall modifications were also detected. In the Al-resistant line, GST6 was identified as one of the key hub genes by co-expression network analysis, and ABC6 may play a role in the downstream regulation of CASP-like 5. In addition, we suggest a class of SWEET transporters that might be involved in the regulation of vacuolar sugar storage and may serve as mechanisms for Al resistance. The results and conclusions expand our understanding of the complex mechanisms involved in Al toxicity and provide a platform for future functional analyses and genomic studies of Al stress in popcorn.
Highlights
Aluminum (Al) is the third most abundant element in the earth’s crust
We present a high-throughput RNA sequencing method to track the transcriptional response of two contrasting popcorn inbred lines, the Al-resistant 11–133 and Al-tolerant 11–60 lines, to uncover candidate genes related to mechanisms of Al toxicity and tolerance in popcorn
We performed a Principal Component Analysis (PCA) to compare the differentially expressed genes (DEGs), which revealed that the DEGs from the control and + Al treatments were clustered together for both lines, but the lines were grouped into separated clusters, showing differences in the genetic background between both inbred lines (Supplementary Fig. S1)
Summary
Aluminum (Al) is the third most abundant element in the earth’s crust. In acid soils with pH values at or below 5, the phytotoxic species A l3+ is solubilized in soil solution and becomes one of the most important abiotic stresses that limit crop production. To study the genetic control of Al tolerance in popcorn, Rahim et al.[24] screened 18 inbred popcorn lines and performed relative root growth (RRG), hematoxylin staining, Al content, scanning electron microscopy, and stereoscopic analyses after seven days of stress treatment (160 μM Al3+) to identify inbred lines with Al sensitivity. They classified the 11–60 line as the most Al-sensitive line with the lowest RRG values, the greatest Al accumulation, and intense epidermal degradation in the root tips. They classified the 11–133 line as an Al-resistant line with the highest RRG value, lowest Al accumulation, and lowest damage to the root apices
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